Mr al-Hilli admitted that he and his brother had been in dispute over ownership of a £825,000 home in Claygate, Surrey, left to them by their mother in 2003, and that one row had become physical but he brushed off anything more serious.

“He (Saad) pinned me down. I was on the bed in my bedroom and he pinned me down. That’s it. That’s all,” he said.

The two men never spoke again except through lawyers, but Mr al-Hilli denied rumours that he had threatened to kill his brother.

Mr Maillaud said: “Saad al-Hilli was afraid of his brother and had changed the locks at the house and fitted a new alarm.”

A motorcyclist and BMW 4x4 which were both seen in the secluded French beauty spot at the time of the killings have been linked to the murder.

A French forestry worker, who saw the BMW, told Panorama that he was convinced it was British because it was a right-hand drive.

He described the driver as “slightly bald and dark skin”.

He claimed two of his colleagues also saw the motorbike rider at one stage because he lifted his visor but all they could say was he “had a bit of a beard”.